4-Trifluoromethylphenol and 2-chloro-4-trifluoromethylphenol are useful intermediates in the preparation of certain substituted phenyl ethers--see for example U.S. Pat. Nos. 3,819,755 and 3,888,932. However, these phenols are rather difficult to synthesise, as the trifluoromethyl group tends to be unstable under a wide range of reaction conditions that might normally be used to introduce a hydroxy group onto a phenyl ring. Accordingly much research has been devoted to the preparation of these compounds, and many possible routes have been described--see for example French Specification No. 1,469,596 and German Pat. No. 1,257,784. All such processes, however, are either chemically or economically unattractive.
Applicants have now found a reaction which unexpectedly gives a novel intermediate that can be used in the preparation of these substituted phenols.